5. A researcher is interested in whether participating
in sports positively influences selfesteem
in young girls. She identifies a group
of girls who have not played sports before
but are now planning to begin participating
in organized sports. She gives them a
50-item self-esteem inventory before they
begin playing sports and administers it
again after six months of playing sports.
The self-esteem inventory is measured on an
interval scale, with higher numbers indicating
higher self-esteem. In addition, scores on
the inventory are normally distributed. The
scores appear below.
Before After
44 46
40 41
39 41
46 47
42 43
43 45
a. What statistical test should be used to
analyze these data?
b. Identify H0 and Ha for this study.
c. Conduct the appropriate analysis.
d. Should H0 be rejected? What should the
researcher conclude?
e. If significant, compute the effect size and
interpret.
f. If significant, draw a graph representing
the data.
6. The student in Question 5 from Module 18
decides to conduct the same study using a
within-subjects design in order to control
for differences in cognitive ability. He selects
a random sample of participants and
has them study different material of equal
difficulty in both the music and no music
conditions. The data appear below. As
before, they are measured on an intervalratio
scale and are normally distributed.
Music No Music
6 10
7 7
6 8
5 7
6 7
8 9
8 8
a. What statistical test should be used to
analyze these data?
b. Identify H0 and Ha for this study.
c. Conduct the appropriate analysis.
d. Should H0 be rejected? What should the
researcher conclude?
e. If significant, compute the effect size and
interpret.
f. If significant, draw a graph representing
the data.
